The overall objective of the proposed studies is to determine the effect of endothelial cell injury on the cell surface and the role of such injury in modulating the inflammatory cell component of the pathogenesis of increased permeability pulmonary edema ("ARDS"). Our focus will be on the effects of injury on the endothelial cell glycocalyx and the relation of changes in the glycocalyx to the adherence of polymorphonuclear neutrophilic leukocytes (PMN) to endothelium. The general approach will be to correlate changes in PMN adherence with ultrastructural histochemistry of the endothelial cell glycocalyx, examined by binding of cationic ferritin and of selected ferritin-conjugated and radiolabeled lectins. Because of inherent limitations of such experiments in vivo, we will use cultured endothelial cells from bovine aorta, main pulmonary artery, and/or human umbilical vein and isolated human PMN. We will determine whether adherence of PMN to cultured endothelium changes with development of a confluent monolayer and whether these changes occur with alterations in endothelial cell glycocalyx. The manner in which PMN adherence and the cell glycocalyx change with cell density has important implications with regard to repair after injury. In order to determine what cell surface constituents modulate PMN adherence, we will investigate the manner in which selected enzyme digestion of confluent monolayers alters PMN adherence and the cell glycocalyx. Since endothelial cell injury may be important in initiating ARDS, we will determine the effects of H202 and endotoxin injury on PMN adherence to cultured monolayers and the relation of changes in adherence to other indices of cell injury (detachment, 51Cr release, and angiotensin converting enzyme activity). We will ascertain whether changes in PMN adherence to injured monolayers are associated with effects on cell surface binding of cationic ferritin and lectins. We will also determine whether changes in PMN adherence and cell surface are reversible after H202 and endotoxin injury. Finally, we will begin to characterize the effects of cell injury on the composition of endothelial cell glycocalyx by assessing cell surface sialic acid and lectin-binding glycoproteins. These studies will lend insights into the role of endothelial cell injury in modulation of PMN function and will further understanding of the pathogenesis of increased permeability pulmonary edema.